[Haskell-cafe] pi

Jonathan Cast jonathanccast at fastmail.fm
Wed Oct 10 20:33:24 EDT 2007

On Thu, 2007-10-11 at 02:11 +0200, jerzy.karczmarczuk at info.unicaen.fr
> Jonathan Cast adds 'something' to a discussion about pi. 
> I commented the statement of Yitzchak Gale, who answered some point
> of Dan Piponi: 
> >> > A default implementation of pi would only increase usability,
> >> > not decrease it.
> I said: 
> >> Can you provide some examples of this "increased usability"?  
> >> 
> >> If possible, with a *relevant* context, which shows that PI should belong
> >> by default to the class Floating (whatever we mean by that...) 
> > 
> > pi /is/ a method of class Floating.  It just doesn't have a default
> > implementation.
> Now, do you have anything to propose, or you just want to criticise
> my wording?

Yes.  I am very eager to criticize your wording.  To wit, I'm still
failing to understand what your position is.  Is it fair to say that
your answer to my question, why pi has no default implementation, is `in
fact, pi shouldn't be a method of Floating anyway'?  If not, I can only
beg for a precise, careful statement of exactly what it is you are
arguing for.

Btw: I am arguing that I (still) don't understand why the line

pi = acos (-1)

or something like it doesn't appear at an appropriate point in the
Standard Prelude, given that the line

pi :: a

appears nearby said point.  I am eager to be enlightened.  But I haven't
been, yet.


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